Microbiology of skin infection Flashcards Preview

Dermatology > Microbiology of skin infection > Flashcards

Flashcards in Microbiology of skin infection Deck (75)
Loading flashcards...
1
Q

Gram positive in clusters

A

Staphylococcus sp

2
Q

Staph saprophyticus

A

Coagnulase negative

3
Q

Test for staph aureus

A

Latex agglutination

4
Q

Does coagulase plasma clot in the bottom of the tube?

A

Yes it does (only staph aureus)

5
Q

Novobicin resistant

A

Staph saprophyticus

6
Q

Neonatal meningitis

A

Group B strep

7
Q

Throat, skin infections

A

Group A strep

8
Q

Commensals, endocarditis

A

Strep viridans

9
Q

Which staph produces coagulase

A

Staph aureus

10
Q

Some strains produce:
• Enterotoxin – food poisoning
• SSSST – staph. scalded skin syndrome toxin
• PVL – Panton Valentine Leukocidin

A

Staph aureus

11
Q

Toxins produced by staph aureus

A

Enterotoxin
SSSST
PVL

12
Q

causes urinary tract infection in women of child-bearing age

A

Staph saprophyticus

13
Q

May cause infection in association with implanted artificial material, such as artificial joints, artificial heart valves, intravenous catheters (produces “slime” that allows it to stick to prosthetic material)

A

Staph epidermis

14
Q

Beta-haemolytic

A

Complete haemolysis

15
Q

Alpha-haemolytic

A

Partial haemolysis

16
Q

Gamma haemolytic

A

No haemolysis

17
Q

Toxin produced by beta-haemolytic streptococci

A

Haemolysin

18
Q

Throat, severe skin infections

A

Group A Beta-haemolytic streptococci

19
Q

How do you further classify beta-haemolytic streptococci?

A

Classify by antigenic structure on surface (SEROLOGICAL GROUPING)
e.g.
– Group A (throat, severe skin infections)
– Group B (meningitis in neonates)

20
Q

Name 2 alpha haemolytic strep

A

Strep pneumonia

Strep viridans

21
Q

Name a non-haemolytic streptococci and where you would find it

A

Enterococcus

  • commensals of bowel
  • common cause of UTI
22
Q

What does sebum (fatty acids) do?

A

Inhibits bacterial growth

23
Q

Competitive bacterial flora of the skin

A

Staphylococcus erpidermidis
Corynebacterium (“diptheroids”)
Proprionbacterium

24
Q

Boils and carbuncles

A

Staph aureus

25
Q

Infected eczema

A

Staph aureus

26
Q

Erysipelas

A

Strep pyogenes (GROUP A STREP)

27
Q

Necrotising fasciitis

A

Strep pyogenes (GROUP A STREP)

28
Q

is a bacterial skin infection involving the upper dermis that characteristically extends into the superficial cutaneous lymphatics. It is a tender, intensely erythematous, indurated plaque with a sharply demarcated border. Its well-defined margin can help differentiate it from other skin infections (eg, cellulitis).

A

Erysipelas

29
Q

Diagnosis of skin infection

A
  • Swab of lesion if surface is broken
  • Pus or tissue if deeper lesion
  • +/- blood cultures, if appropriate
30
Q

Green vial

A

Aerobic culture bottle

31
Q

Red/pink vial

A

Anaerobic culture bottle

32
Q

Yellow vial

A

Paediatric culture bottle

33
Q

Antibiotic for strep pyogenes (Group A strep)

A

Penicillin (will also be treated by flucloxacillin)

34
Q

Tinea capitis

A

Scalp

35
Q

Tinea barbae

A

Beard

36
Q

Tinea corporis

A

Body

37
Q

Tinea manuum

A

Hand

38
Q

Tinea unguium

A

Nails

39
Q

Tinea cruris

A

Groin

40
Q

Tinea pedis

A

Foot

41
Q

How do dermatophytes enter the skin?

A

Enter abraded or soggy skin

42
Q

In which layer do hyphae spread?

A

Spread in stratum corneum

43
Q

Which type of tissue do dermatophytes infect?

A

Infects keratinised tissues only (skin,hair,nails)
•Increased epidermal turnover causes scaling
• Inflammatory response provoked (dermis)
• Hair follicles and shafts invaded

44
Q

Lesion grows outward and heals in centre, giving a “ring” appearance

A

Dermatophyte

45
Q

Males or females more commonly affected in dermatophyte infections?

A

Males

46
Q

Who are more commonly affected by scalp ringworm?

A

Children

47
Q

Foot and groin ringworm mainly affects who?

A

Men

48
Q

Anthropophilic fungi

A

Other infected humans

MOST LIKELY

49
Q

Zoophilic fungi

A

Animals (cats, dogs, cattle)

50
Q

Geophilic fungi

A

Soil (less common in UK)

51
Q

Dermatophyte infections, sources of infection

A

Other infected humans (MOST LIKELY)

Animals

Soil

52
Q

How is trichophyton rubrum spread?

A

Human-human transmission

53
Q

How is trichophyton mentagraphytes spread?

A

Human-human transmission

54
Q

How is microsporum canis spread?

A

Cats, dogs-humans

55
Q

Dermatophyte infection diagnosis

A
Clinical appearance
• Woods light (fluorescence)
• Skin scrapings, nail clippings, hair
– Send to laboratory in a “Dermapak” for microscopy and culture
– N.B. Culture takes 2 weeks +
56
Q

Where should skin scrapings be taken from?

A

Taken from the edge of the scaly lesion

57
Q

Treatment for small areas of infected skin, nails

A

Clotrimazole (canestan) cream or similar

Topical nail paint (amorolfine)

58
Q

Treatment for scalp dermatophyte infections

A

Terbinafine ORALLY

Itraconazole ORALLY

59
Q

Diagnosis of candida?

A

Swab for culture

60
Q

Where would you get candida infection?

A

Candida causes infection in skin folds where area is warm and moist “candida intertrigo”
Seen under the breasts in females, groin areas, abdominal skin folds etc, nappy area in babies

61
Q

Treatment for candida?

A

Clotrimazole cream

Oral fluconazole

62
Q

What type of skin infection is scabies?

A

Parasitic

63
Q

Infection caused by Sarcoptes scabiei

A

Scabies

64
Q

Scabies incubation period?

A

6 weeks

65
Q

Intensely itchy rash affecting finger webs, wrists, genital area

A

Scabies

66
Q

Treatment for scabies

A

malathion lotion, applied overnight to whole body and washed off next day
– benzyl benzoate (avoid in children)

67
Q

Where would you get scabies?

A

Finger webs, wrists, genital areas

68
Q

This parasitic infection burrows in your skin and makes “tracts”

A

Scabies

69
Q

Pediculus capitis

A

Head louse

70
Q

Pediculus corporis

A

Body louse

71
Q

Vagabond’s disease

A

Pediculus corporis (body louse)

72
Q

Plithirus pubis

A

Pubic louse

73
Q

Treatment for lice (pediculosis)

A

Malathion lotion

74
Q

Which type of bacteria can survive in the environment because of their cell wall structure?

A

Gram positive

-these may become a source of infection for other patients

75
Q

WHO NEEDS SINGLE ROOM ISOLATION

A

Group A strep
MRSA
Scabies (also need long sleeved gown)